11,210 research outputs found
5-ht inhibition of rat insulin 2 promoter cre recombinase transgene and proopiomelanocortin neuron excitability in the mouse arcuate nucleus
No full textA number of anti-obesity agents have been developed that enhance hypothalamic 5-HT transmission. Various studies have demonstrated that arcuate neurons, which express proopiomelanocortin peptides (POMC neurons), and neuropeptide Y with agouti-related protein (NPY/AgRP) neurons, are components of the hypothalamic circuits responsible for energy homeostasis. An additional arcuate neuron population, rat insulin 2 promoter Cre recombinase transgene (RIPCre) neurons, has recently been implicated in hypothalamic melanocortin circuits involved in energy balance. It is currently unclear how 5-HT modifies neuron excitability in these local arcuate neuronal circuits. We show that 5-HT alters the excitability of the majority of mouse arcuate RIPCre neurons, by either hyperpolarization and inhibition or depolarization and excitation. RIPCre neurons sensitive to 5-HT, predominantly exhibit hyperpolarization and pharmacological studies indicate that inhibition of neuronal firing is likely to be through 5-HT1F receptors increasing current through a voltage-dependent potassium conductance. Indeed, 5-HT1F receptor immunoreactivity co-localizes with RIPCre green fluorescent protein expression. A minority population of POMC neurons also respond to 5-HT by hyperpolarization, and this appears to be mediated by the same receptor-channel mechanism. As neither POMC nor RIPCre neuronal populations display a common electrical response to 5-HT, this may indicate that sub-divisions of POMC and RIPCre neurons exist, perhaps serving different outputs. (C) 2009 IBRO. Published by Elsevier Ltd. All rights reserved.</p
Mitochondrial phylogeny reveals the artificial introduction of the pale chub Zacco platypus (Cyprinidae) in Taiwan.
No full textEfeitos da administração sistêmica de 5-HT e 8-OH-DPAT sobre os estados de vigília e sono de pombos (Columba livia)
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-Graduação em NeurociênciasInvestigar a participação dos mecanismos serotonérgicos sobre a regulação dos estados de sono e vigília em pombos por meio da caracterização comportamental e eletrográfica hipocampal dos estados de sono e vigília após administração sistêmica de 5-HT ou 8-OH-DPAT e quantificação dos efeitos da administração de 5-HT ou 8-OH-DPAT sobre a atividade eletrográfica hipocampal dos diferentes estados identificados
AFLPs congruent with morphological differentiation of Asian common minnow Zacco in Taiwan (Pisces: Cyprinidae).
No full textA novel model to study the in vitro effects of oxidative stress on the DNA mismatch repair system.
No full textThe Effects of Serotonin Receptor Antagonists on Contraction and Relaxation Responses Induced by Electrical Stimulation in the Rat Small Intestine
No full textBackground: The main source of 5-HT in body is in enterchromafin cells of intestine, different studies mentioned different roles for endogenous 5-HT and receptors involved and it is not clearified the mechanism of action of endogenous 5-HT.
Objectives: To study the role of endogenous 5-HT on modulation of contraction and relaxation responses induced by electrical field stimulation (EFS) in different regions of the rat intestine.
Materials and Methods: Segments taken from the rat duodenum, jejunum, mid and terminal ileum were vertically mounted, connected to a transducer and exposed to EFS with different frequencies in the absence and presence of various inhibitors of enteric mediators i. e. specific 5-HT receptor antagonists.
Results: EFS-induced responses were sensitive to TTX and partly to atropine, indicating a major neuronal involvement and a cholinergic system. Pre-treatment with WAY100635 (a 5-HT1A receptor antagonist) and granisetron up to 10.0 µM, GR113808 (a 5-HT4 receptor antagonist), methysergide and ritanserin up to 1.0 µM, failed to modify responses to EFS inall examined tissues. In the presence of SB258585 1.0 µM (a 5-HT6 receptor antagonist) there was a trend to enhance contraction in the proximal part of the intestine and reduce contraction in the distal part. Pre-treatment with SB269970A 1.0 µM (5-HT7 receptor antagonist) induced a greater contractile response to EFS at 0.4 Hz only in the duodenum.
Conclusions: The application of 5-HT1A, 5-HT2, 5-HT3, 5-HT4, 5-HT6 and 5-HT7 receptor antagonists, applied at concentrations lower than 1.0 µM did not modify the EFS-induced contraction and relaxation responses, whichsuggests the unlikely involvement of endogenous 5-HT in mediating responses to EFS in the described test conditions.
Keywords: Electric Stimulation Therapy; Serotonin 5-HT1 Receptor Antagonists; Intestine, Smal
Efeitos comportamentais e sobre a expressão da proteina Fos em neurônios serotonérgicos após injeções intracerebroventriculares de serotonina em pombos (Columba livia)
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Neurociências, Florianópolis, 2010Em mamíferos, os circuitos serotonérgicos têm sido relacionados à modulação de comportamentos ingestivos e dos estados de sono e vigília. No presente trabalho, foram examinadas as respostas comportamentais e ingestivas e também o padrão de expressão da proteína Fos no tronco encefálico, após injeção intracerebroventricular de serotonina (5-HT, 50, 150 ou 300 nmol/2µl) em pombos (Columba lívia) com livre acesso à água e alimento. As injeções de 5-HT provocaram marcante sequência comportamental que consistiu em veemente ingestão de água dentro dos primeiros 15 minutos após os tratamentos, seguida por comportamentos de manutenção e então por prolongados períodos de comportamentos típicos de sono. Estes efeitos foram de curto-prazo: os padrões de ingestão de água foram similares entre animais tratados com 5-HT ou veículo 2, 3 e 24 h após as injeções. Nenhum efeito consistente foi observado sobre a ingestão de alimento. A densidade de células imunorreativas à Fos (Fos+) ou tanto à Fos e a triptofano hidroxilase (Fos+/TPH+) foram examinadas em seis áreas do tronco encefálico rostral em pombos com livre acesso à água e alimento que foram tratados com 5-HT (5-HTW) ou veículo. Um grupo controle adicional foi tratado com 5-HT, mas não teve acesso à água nas duas horas seguintes à injeção (5-HTØ). Na rafe pontina, a densidade Fos+ foi positivamente correlacionada com índices de comportamentos típicos de sono e aumentou tanto nos animais 5-HTW como nos animais 5-HTØ. No núcleo da linha média pontomesencefálica, o linearis caudalis, as marcações Fos+ e Fos+/TPH+ foram negativamente correlacionadas com os comportamentos típicos de sono e foram reduzidas nos animais 5-HTØ. Na área de A8, a densidade de Fos+/TPH+ foi reduzida VII em ambos os grupos tratados com 5-HT e foi positivamente correlacionada com a ingestão de alimento e negativamente correlacionada com o sono. Estes dados indicam que efeitos hiperdípsicos e hipnóticos de injeções ICV de 5-HT em pombos com livre acesso à água e alimento resultam da inibição da atividade tônica de neurônios serotonérgicos no tronco encefálico. Além disso, indicam que pode existir em aves, semelhante a mamíferos, uma influência inibitória de neurônios serotonérgicos sobre o comer, o beber e sobre o sono, possivelmente relacionados à sequência de saciedade pós-prandial e que a coordenação deste cenário fisiológico por circuitos serotonérgicos pode representar um atributo altamente preservado no encéfalo de amniótas.In mammals, serotonergic circuits have been shown to play important roles in the control of ingestive behaviors and sleep-waking states. In the present work, the behavioral and ingestive responses as well as the pattern of Fos-like activity in the brainstem following intracerebroventricular (ICV) injections of serotonin (5-HT at 50, 150 or 300 nmol/2 µl) were examined in free-feeding/free-drinking pigeons (Columba livia). 5-HT injections evoked a remarkable behavioral sequence that consists of vehement drinking behavior within the first 15 min after injections, followed by preening and then by prolonged periods of sleep-like behavior. These effects are short-lived: the patterns of ingestive behavior are similar in 5-HT- and vehicle-treated animals at 2, 3 and 24 h after treatments. No consistent effect on feeding behavior was observed. The density of cells immunoreactive to Fos (Fos+) or to both Fos and tryptophan hydroxylase (Fos+/TPH+) were examined in six areas of the rostral brainstem of ree-feeding/freedrinking birds treated with 5-HT (5-HTW) or vehicle. An additional control group was treated with 5-HT without access to water during the 2 hours after the treatment (5-HTØ). In the pontine raphe, Fos+ density positively correlated to sleep behavioral indexes and increased in both 5-HTW and 5-HTØ animals. In the midline nucleus linearis caudalis, Fos+ and Fos+/TPH+ labeling negatively correlated to sleep-like behaviors and were reduced in 5-HTØ animals. In the A8 area, Fos+/TPH+ cell density was reduced in both 5-HTW and 5-HTØ animals and was positively correlated to food intake whereas negatively correlated to sleep. These data indicate that hyperdipsic and hypnotic effects of ICV 5-HT in free-feeding pigeons results from inhibition of the tonic activity of serotonergic neurons in brainstem. Moreover, it indicates that it may exist in IX birds, as in mammals, an inhibitory influence of serotonergic neurons on feeding, drinking and sleep behaviors, possibly related to the postprandial Behavioral Satiety Sequence and that the coordination of this physiological set by central 5-HT circuits may represent a highly conserved attribute of the amniote brain
Risk analysis of High-Temperature Aquifer Thermal Energy Storage (HT-ATES)
No full textThe storage of heat in aquifers, also referred to as Aquifer Thermal Energy Storage (ATES), bears a high potential to bridge the seasonal gap between periods of highest thermal energy demand and supply. With storage temperatures higher than 50 °C, High-Temperature (HT) ATES is capable to facilitate the integration of (non-)renewable heat sources into complex energy systems. While the complexity of ATES technology is positively correlated to the required storage temperature, HT-ATES faces multidisciplinary challenges and risks impeding a rapid market uptake worldwide. Therefore, the aim of this study is to provide an overview and analysis of these risks of HT-ATES to facilitate global technology adoption. Risk are identified considering experiences of past HT-ATES projects and analyzed by ATES and geothermal energy experts. An online survey among 38 international experts revealed that technical risks are expected to be less critical than legal, social and organizational risks. This is confirmed by the lessons learned from past HT-ATES projects, where high heat recovery values were achieved, and technical feasibility was demonstrated. Although HT-ATES is less flexible than competing technologies such as pits or buffer tanks, the main problems encountered are attributed to a loss of the heat source and fluctuating or decreasing heating demands. Considering that a HT-ATES system has a lifetime of more than 30 years, it is crucial to develop energy concepts which take into account the conditions both for heat sources and heat sinks. Finally, a site-specific risk analysis for HT-ATES in the city of Hamburg revealed that some risks strongly depend on local boundary conditions. A project-specific risk management is therefore indispensable and should be addressed in future research and project developments.Accepted Author ManuscriptWater Resource
Ht-index calculator v1.0
No full text<p>The first release of Ht-index calculator, which is a winform application for obtaining related metrics of head/tail breaks applying on a single data array.</p>
Improving identification of HT-ATES performance drivers and -barriers
No full textHigh temperature aquifer thermal energy storage (HT-ATES) can potentially solve the mismatch between heat supply and demand. It can provide a large scale seasonal heat storage solution. Thereby it enables an increase in full load hours of the base heat source, which can benefit project performance on both costs and emissions. However, the limited number of successful pilot projects indicates the technology has not escaped its state of infancy. There is a gap from concept to implementation, which is signified by the disagreement of experts on performance drivers and barriers of HT-ATES. This research aims to narrow the described knowledge gap, by improving identification of HT-ATES performance drivers and barriers. Thereby it strives to improve decision making of HT-ATES implementation, and further enhance future HT-ATES application in heating projects. The broad scope of research demands both a diagnostic and design-orientated approach, and fits seamlessly with a multi-criteria decision analysis. The analysis entails the stages of creating, evaluating, comparing and ranking of case-specific scenarios. Parametric variation changes the conditions for HT-ATES implementation across the scenarios. A simulation model is developed and connected to a groundwater model to apply the parametric variation, to create the different scenarios, and consequently to produce the quantitative information for further evaluation. During the stages of creating, evaluating, comparing and ranking, the methodology systematically produces new results on the opportunities and risks introduced by HT-ATES, and additionally on the HT-ATES performance drivers and barriers. The results show that HT-ATES enables the opportunity of improving project performance with respect to the internal rate of return and emissions. Groundwater impact remains the greatest risk, but it can be minimised with smart decision making. To support the decision maker and to overcome the risk of groundwater impact, the research proposes several performance-enhancing, non-explicit guidelines. The guidelines focus on realising an HT-ATES implementation, where project performance with respect to internal rate of return, emissions and groundwater impact are balanced. Thereby they explain the major HT-ATES performance drivers and barriers. The guidelines are summarised below. The decision maker is recommended to .. 1. .. minimise the uncertainty, through thorough subsurface characterization before implementation. Secondly, to focus on aquifers with a minimum depth of 200 [m] and a minimum hydraulic conductivity of 5 [m/d] 2. .. assure network return temperatures during peak demand are below expected storage temperatures 3. .. not consider project life-times exceeding 20 years 4. .. assure yearly maximum base source heat production is always lower than yearly consumer heat demand 5. .. to strive for a flat demand curve and apply peak-shaving, by means of, for example, variable heat prices Currently, the guidelines have the purpose of giving direction to the decision maker, but they will become more explicit once the methodology is improved, and the uncertainty and number of assumptions in the model is decreased.Electrical Engineering | Sustainable Energy Technolog
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